Study on the Mechanical Performance of Prefabricated Trench Cable Tunnel Joint

Prefabricated trench cable tunnel (TCT) has the characteristics of small sections, shallow buried depth and complex laying conditions, and its joint stiffness and bearing capacity have great influences on the normal use of the tunnel. Three groups of full-scale bolted cable tunnel members tested for flexural and shear resistances of joints, and the mechanical parameters of joints were analyzed by verifying the finite element model of the TCT. The influences of design parameters such as number of bolts, pre-tension force, axle angle length and edge length on the mechanical behavior of joint were determined. The results show that: The shear capacity and stiffness of 4 bolts are increased by 59.4% and 102.1% respectively compared with 2 bolts. For each 30 kN increase in bolt pretension, the bending and shear stiffness is increased by 1.5×10~5 kN m/rad, 160 kN/mm; The bending and shear bearing capacity of axle corner is increased by 50kN and 20kN respectively when the length of axle edge is increased by 25 mm. When the UHPC (Ultra-High Performance Concrete) material is used to strengthen the armpit corner of the weak point of the cable tunnel, the bending shear capacity and the bending shear rigidity are increased by 80% and 105% respectively, and 50% and 95% respectively. The research results can provide reference for the design and engineering application of prefabricated TCT.